Hints are not remembered when game is quite, although the sudoku itself was saved. When traveling / commuting at some point in time one must stop with the game. At this moment ksudoku does not remember the hints :( As it is quite a lot of work to determine the hints again, it would be very good to save the hints too.
I think you mean the small numbers called markers or notes. They were being saved but not re-loaded. That bug was fixed in KSudoku in the KDE 4.8 release (January 2012) and there were many other improvements in the game at that time, such as making the difficulty selection work properly. *** This bug has been marked as a duplicate of bug 188162 ***
In meant the markers / notes indeed. Thank you for your swift reply and thank you for making loading the markers. I'll see if I can get hold of a newer ksudoku version.